The cold desert is inhospitable
to life. The valleys in the interior of Antarctica and the snowy
tops of high mountains cannot support life: birds or insects
may visit there, but the cold keeps plants from growing. Without
plants, there can be no animals because there is nothing for
animals to eat.

The shores of both the arctic
and the antarctic have animals that find their food in the ocean.
The waters of the antarctic support plankton, which includes
unicellular plants. These tiny plants photosynthesize during
the antarctic spring and summer, and become the primary
producers of a food chain that nourishes animals on land
as well as in the sea. This is the first
trophic level of this system.

Food production in this system
varies with the seasons. In winter, when the south pole is in
darkness, there is no light for photosynthesis, and so no plant
growth. In spring, deep ocean currents bring up nutrients from
the ocean bottom, and the plankton grows rapidly with both light
and food. The animials that live on it grow and reproduce. Later
in the year there are fewer nutrients, and growth slows. Some
of the animals swim away to areas with more food.

We will look at this system
in the spring, when there is lots of food The plankton provides
food for the next level of life forms.

Tiny animals, such as krill
(a kind of tiny shrimp) and very small fishes, feed on the plankton.
They become the primary consumers, taking on the
role of herbivores and becoming the
second trophic level
of this system.

It is difficult to imagine how
rich these waters are. They are so full of living creatures that
they are almost a soup! The third trophic
level, the carnivores, includes
larger fishes, squid, seals, penguins, and huge whales, such
as baleen whales, that eat enormous numbers of the krill.

Seals
and penguins come onto land to reproduce, but are otherwise well-adapted
to life in the ocean. They find all their food in the water.
In the water they also become prey for the Killer Whale, the
top predator in this biome. Killer whales are tertiary
consumers, and occupy the fourth
trophic level.

This diagram shows how the Kilocalories
move up the food chain at this time. Remember, we are looking
at spring with abundant food here. In another season there will
not be so much energy available to distribute.